Question

Two polaroids $A$ and $B$ are kept with their transmission axis at an angle $\theta$ with respect to one another. If the transmitted intensity of light is $I_t=0.75I_0$, where $I_0$ is the intensity of light incident on the system, then $\theta$ is:

• A. ${30}^0$
• B. ${45}^0$
• C. ${60}^0$
• D. ${90}^0$

Answer 1

Answer: (A)

${30}^0$

$I_t=I_0{\cos }^2\theta$

$\Rightarrow 0.75I_0=I_0{\cos }^2\theta$

$\Rightarrow {\cos }^2\theta =\frac{3}{4}$

$\Rightarrow \theta ={30}^0$